Focused ion beam preparation of atom probe specimens containing a single crystallographically well-defined grain boundary

TL;DR

This paper presents a novel focused ion beam method to prepare atom probe specimens with a single, well-characterized grain boundary, enabling detailed analysis of solute segregation at the boundary.

Contribution

The study introduces a new FIB preparation technique for atom probe specimens containing a single, crystallographically defined grain boundary, facilitating precise segregation analysis.

Findings

Successful preparation of atom probe specimens with a single grain boundary.

Unambiguous identification of the grain boundary in atom probe tips.

Ability to analyze solute segregation at specific grain boundaries.

Abstract

Needle-shaped atom probe specimens containing a single grain boundary were produced using the focused ion beam (FIB) of a dual-beam FIB/SEM (scanning electron microscope) system. The presented specimen preparation approach allows the unprecedented study of a grain boundary which is well characterised in its crystallographic orientation by means of the field ion microscope (FIM) and the tomographic atom probe (TAP). The analysis of such specimens allows in particular the determination of solute excess atoms at this specific grain boundary and hence the investigation of the segregation behaviour. The crucial preparation steps are discussed in detail in the present study for the S 19a {331} <110> grain boundary of a 40 at.ppm-Bi doped Cu bi-crystal. Transmission electron microscope (TEM) images and TAP analyses of the atom probe tips demonstrate unambiguously the presence of the selectively prepared grain boundary in the apex region of some of the specimens.